Flux bags may be manufactured using a process known as the form/fill/seal process, wherein a flux bag is formed from a gusseted, tubular sheath known as bag stock. Typically, the bag stock is four layers thick in the gusseted regions but only two layers thick in the remaining non-gusseted regions of the sheath. During the sealing process, the thicker gusseted regions are exposed to higher pressures by the heat seal bands and seal bar(s), while the remaining non-gusseted regions are subjected to relatively lower pressures. This uneven pressure often results in voids in the seal at the transition between the gusseted and non-gusseted regions of the bag, which may result in spilling of the flux from the bag, contamination of the contents of the bag, and/or moisture absorption by the flux contained within the bag.